First trap versatile image is initramfs and not initrd. So I integrated
the cpio archive into my kernel and booted the Debian installer. But it
is really netboot.

This is correct; the 'netboot' installer image does not contain the
necessary kernel modules and d-i components to retrieve software from
CD-ROM.

The first thing it makes is to detect network
hardware. Then networking will be configured so first packages are
downloaded from one of the mirrors. I don't find any option to make
installation from the CD/DVD. What is the main difference between
"cdrom" and "netboot" versions? Can it be configured within cpio via
changing some scripts or so?

If you boot the installer in expert mode, you should be able to select
additional udebs at some point. If I'm not mistaken, that list should
contain an entry 'cdrom-retriever'. If you enable that, you should be
able to install from CD-ROM.
Haven't tested that, however.